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Topic: My WFO design (Read 13894 times)

You use the lower flue for pre-heating the oven, but during the bake, when you want the smoke away from the pizza, you use the upper flue.

Not a bad idea- you just need a damper for each flue. I will probably just go with a noborigama (climbing kiln) style firebox- the first dome in this picedit: during trial runs, if the floor gets too hot, I'll slow down the fire, which lets it rise across the dome.

That picture's impressive. I take it the firebox is on the left, and the heat/combustive gasses are ducted through the two ovens?

If you are going to craft a pizza/bread oven built on this concept, you should name it, maybe even think about patenting it. I don't say that lightly- I know how tough it is to patent something. I think your concept is very interesting, and I really want to see it come to realization. It's an ancient oven-building technique, which in these days of mass-production doesn't get the replication it deserves.

Pizzaneer- yes- the lower dome is the firebox for the kiln. There's a mess of crossdraft designs- some noborigamas have several chambers and take a couple weeks to fire, people working around the clock. Not sure if it rises to patentability- I know more than one person that heats a pizza oven with residual kiln heat. My kiln has a "Bourry box" design. The advantage of that is that a large charge of wood can be put in at once, and the air always goes through the fuel until it's burned to coals.

Heres a wfo that a guy built next to his 4 chamber kiln in Seagrove, NC (pottery capital of the US)- I assume he built this for fun while he was firing the big kiln next to it (I took a mess of kiln pics there- but only one pizza oven pic). I think they just shovel coals out of the kiln into this to heat it- the kiln coals get feet deep.

notice the baby kiln built on the left of it. He has his kids out there making pots etc in the studio- I'd bet that was their first kiln build

scott123

AP, one thing to keep in mind- if you have any hope of getting proper pizza making temps, you should be shielding the floor from any direct heat from the firebox. The goal should be a freakishly hot ceiling that then heats the floor via IR. Firebox heats ceiling, ceiling heats floor.

AP, one thing to keep in mind- if you have any hope of getting proper pizza making temps, you should be shielding the floor from any direct heat from the firebox. The goal should be a freakishly hot ceiling that then heats the floor via IR. Firebox heats ceiling, ceiling heats floor.

Thanks! Thinking about it like that helps. The firebox will be lower, and the flues relatively small, which *I think* should created enough of a barrier.

That's all being stored- I was curious why they did that- maybe it's how they measure what they'll need. A fire is started in the lowest chamber- when the first ware chamber is hot, they start adding wood through a hole ("side stoking") the next dome is fired, when that's hot, they stoke the next, and so on- that's why it takes so long

This design isn't really a white oven, and the best I have seen neither are most of the big old coal ovens. With a firebox bellow the oven that directly heats the oven chamber this is closest in design to a french Guillard bread oven. Getting this design to pizza temperatures with the proper balance of top and bottom heat is gonna be tough. I personally think your two best options would be:

1. Fully insulate between the floor and and firebox bellow and then build an adjustable throat where the flame enters the oven chamber. This throat can be used to direct the flame down to the floor during heat-up and then change the angle to provide top heat during cooking once the floor is charged.

2. Build a removable layer of insulation that sits between the firebox and the cooking floor. It would be removed during heat up to heat the floor, once the floor is charged it would be put in place to stop the floor from super heating while bringing the dome up to cooking temperature and during cooking.

This design isn't really a white oven, and the best I have seen neither are most of the big old coal ovens. With a firebox bellow the oven that directly heats the oven chamber this is closest in design to a french Guillard bread oven. Getting this design to pizza temperatures with the proper balance of top and bottom heat is gonna be tough. I personally think your two best options would be:

1. Fully insulate between the floor and and firebox bellow and then build an adjustable throat where the flame enters the oven chamber. This throat can be used to direct the flame down to the floor during heat-up and then change the angle to provide top heat during cooking once the floor is charged.

2. Build a removable layer of insulation that sits between the firebox and the cooking floor. It would be removed during heat up to heat the floor, once the floor is charged it would be put in place to stop the floor from super heating while bringing the dome up to cooking temperature and during cooking.

All reasons I went to the offset firebox design (crossdraft) rather than the under floor.

All reasons I went to the offset firebox design (crossdraft) rather than the under floor.

I haven't been around much this week, I saw that proposed, guess in my skimming I didn't notice you had changed your plans.

At this point it becomes very similar to an old style coal oven. Where do you plan to locate the flu openings? Will you have a secondary flue opening above the door to catch the smoke when it is open? I think you are on the path to a functional oven now, but I do think it is a design more suited to East Coast US style pizza cooked in 3 or 4 minutes. Is that what you are after?

If it's good enough to make pottery, with all the complicated glazes (thats COMPLICATED), simple bottom - top heat calculations at a relatively low temp should be easy. I like the crossdraft, U-shape supply with adjustable vent. It's close in concept to the LBE. Can you take some pictures of the other potter's ovens? Are they much different?

I'm really looking forward to seeing how it turns out, with you and Meesh collaborating. I live in an area with lots of good clay, plentiful firewood, and my wife used to make pottery in a little kiln - I'm thinking of giving this a try too.

I haven't been around much this week, I saw that proposed, guess in my skimming I didn't notice you had changed your plans.

At this point it becomes very similar to an old style coal oven. Where do you plan to locate the flu openings? Will you have a secondary flue opening above the door to catch the smoke when it is open? I think you are on the path to a functional oven now, but I do think it is a design more suited to East Coast US style pizza cooked in 3 or 4 minutes. Is that what you are after?

Plan is to have the oven hot enough that I can have good coals/no smoke when it's time to cook. I would hope for a 90 second pizza, and if it's 3 minutes I won't be disappointed- while I love pizza as much as the next guy, I don't have the experience to appreciate/demand a specific style.

The "throat", from the firebox, will be low so that heat rises and rides up the dome. The flue to the chimney will be low on the other side of the dome- this increases the interaction between the heat and the dome by maximizing the residence time. This design requires a higher chimney to get to kiln temps- Olsen says 3' for each 1' dome height, plus 1' for each 3' lateral travel from firebox to chimney. I don't need to get to 2400F, but chimney brick is cheap (can use commons), and I can damper down as much as I like- so I might have a 5' chimney.

If it's good enough to make pottery, with all the complicated glazes (thats COMPLICATED), simple bottom - top heat calculations at a relatively low temp should be easy. I like the crossdraft, U-shape supply with adjustable vent. It's close in concept to the LBE. Can you take some pictures of the other potter's ovens? Are they much different?

I'm really looking forward to seeing how it turns out, with you and Meesh collaborating. I live in an area with lots of good clay, plentiful firewood, and my wife used to make pottery in a little kiln - I'm thinking of giving this a try too.

Pottery and pizza are very different things. Pottery kilns take a long time to heat with the goal being an even temperature throughout. That's not what we are after with pizza. For home use getting the hearth to 900F in an hour and a half like you can in a black oven is going to be the design challenge. Not saying it can't be done, but it will take design work to get the heat down to the floor. Reverb furnaces for melting metal are also very similar to this. They require lots of design for a throat that directs the heat down on the hearth.

It's a lot of fun isn't it. Nice to run across somebody who doesn't think people are being jerks, just trying to help.

Absolutely. I'm confident that I can "make stuff hot" as well as the next guy- but that doesn't mean I can build a proper appliance for making pizza, blowing glass, or smelting ore.

Talking about where the heat goes makes me think of my early struggles in firing my kiln properly (everyone ruins pots in learning a new kiln)- but it turns out that a tall chimney can be made to suck fire down low in a kiln (I used to over fire the bottom stacks). Slowing the fire (using the damper) gets more heat up top. I'll run a couple test fires to learn this "kiln" as well.

pizzaneer- here's some shots of my kiln. The firebox is a "Bourry box"- 40" wide wood is suspended above the coal bed- primary air is sucked through the wood charge, so it effectively burns upside down. The fire gets superheated as it approaches the coal bed. The firebox shot shows the "throat" area as well. This firebox design has a number of advantages,including the ability to put a lot of wood in, and that the wood shields you from the intense heat in the kiln (some other designs will catch you on fire from radiative heat if you aren't careful).

The pic with me loading shows the flue area- the vent to the chimney. They go all the way across to even flow, and I have "passive dampers" that I can use to direct heat left and right to even out a firing.

The fire pic is me next to the firebox during a "reduction" cycle- getting the burn to be inefficient at certain times actually helps with clay and glaze colors. With the draft slowed way down, the gases produced by the heating wood create a back pressure, and the hot gases combust when they hit air.

The idea of improving upon 5000+ years of baking experience seems to be a bit of a waste of time to me. If you are trying for a new type or style of cooking I can see it, but realistically, the problem was been solved and refined to a high degree. What is the point? Do you want to have a combo kiln/oven?

The idea of improving upon 5000+ years of baking experience seems to be a bit of a waste of time to me. If you are trying for a new type or style of cooking I can see it, but realistically, the problem was been solved and refined to a high degree. What is the point? Do you want to have a combo kiln/oven?

No, I just want to have fun.

I admit that I have that damn Cindy Lauper song in my head now. I hope to have a combo oven and smoker.

pizzaneer- here's some shots of my kiln. The firebox is a "Bourry box"- 40" wide wood is suspended above the coal bed- primary air is sucked through the wood charge, so it effectively burns upside down. The fire gets superheated as it approaches the coal bed. The firebox shot shows the "throat" area as well. This firebox design has a number of advantages,including the ability to put a lot of wood in, and that the wood shields you from the intense heat in the kiln (some other designs will catch you on fire from radiative heat if you aren't careful).

The pic with me loading shows the flue area- the vent to the chimney. They go all the way across to even flow, and I have "passive dampers" that I can use to direct heat left and right to even out a firing.

The fire pic is me next to the firebox during a "reduction" cycle- getting the burn to be inefficient at certain times actually helps with clay and glaze colors. With the draft slowed way down, the gases produced by the heating wood create a back pressure, and the hot gases combust when they hit air.

SEE? I TOLD you guys, this is more complicated than pizza! Man, a pizza- making kiln... not since the days of the old coal-fired bread ovens that were adapted for pizza. Ground-up design, and someone who is welcoming input into how to make an ideal cooking situation for pizza. C'mon you WFO ppl!

In my opinion, it is not worth the effort. You end up with an appliance that is "OK" for the multiple uses, but not optimized for either. Better to build the smoker next to the oven, or the fireplace next to oven, or the grill next to the oven, rather than try and bastardize a combination that is a compromise of both.